Cha > Dex > Str (13+)> Con > Int (10+) > Wis (dump): Basically, this Knight has three goals:
1) Get access to
Standstill, Combat Reflexes, Mage Slayer (Complete Arcane), Supernatural Opportunist (Tome of Magic), and Frightful Presence (Draconomicon).
2) Getting ridiculous reach. This can be accomplished a number of ways:
Play a big race (try to avoid LA)
Reach Weapon: Doubles reach.
Polymorph: Ask a friend to turn you into something bigger.
Expansion (doesn't stack with Enlarge Person): +1 or +2 size.
Alter Self (doesn't stack with Enlarge Person or Expansion): +1 size.
Giant Size (Wu Jen 7, Comp Arcane pg 109): Grow to Huge size or bigger.
Willing Deformity -> Deformity Tall (Heroes of Horror): +5 ft.
Aberration Blood -> Inhuman Reach (Lords of Madness): +5 ft.
Extended Reach (req tentacle like limbs, provided by Inhuman Reach): +5 ft.
3 levels of Warshaper (Comp Warrior): +5 ft, but only with natural weapons.
Some of these options aren't a good choice for this build, but I'd though I'd put them out there anyway. But it should be relatively easy for you to get 30+ feet of reach with a moderate investment. If necessary take the Arcane Schooling (Player’s Guide to Faerun pg 33) or invest in UMD. Even cross class, as a Cha based build you shouldn't have trouble using it.
3) Find a way to consistently deal 40ish damage per hit - not very hard with decent Str, a two handed weapon magic weapon, etc. This will make the Reflex Saves needed to accomplish any type of movement and the Concentration checks needed to cast ridiculously hard.
Put these together with your Knight class abilities (Bulwark of Defense, Vigilant Defender, Daunting Challenge, Test of Mettle) and basically everyone within your reach will be screwed one way or another. You can stop movement, create difficult terrain, impose a penalty on Tumble, force enemies to attack you, can use a Fear effects, will get bonus AoO, and prevent spellcasting. Stand near the party Wizard or whoever needs to be protected the most, and the enemies will come to you, even without Test of Mettle.
The down side of this build is that it really doesn't come together until at least ECL 12ish, if not much higher. It lacks any big damage dealing combo, though you could certainly add some at high levels. And your DM is definitely going to use lots of very long range enemies against you, so be prepared.